Remove sharp or jagged edges in mesh
This topology is so messed up (current Sculpt Mode will do that), it might need a retopology.

Either use a Shrinkwrap Modifier to get a clean result with a new mesh and far less verts (after the rough adjustments, you can enable the modifier to be active during Edit Mode which glues your verts to the surface) or use use the Bsurfaces addon. With it, you can convert Grease Pencil strokes into topology. You need to set the grease pencil to Surface or otherwise the strokes won't connect to the underlying mesh.